Insulator



I JACKSON INSULATOR March 29 1927.

Filed June 5 1921 INVENTOR ia fjclzyksazz BY 40 WITNESSES:

ORNEY Patented Mar. 29, 1927.

UNITED STATES RAY I. JACKSON, OF EDGEWOOD PARK, PENNSYLVANIA,

ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

INSULATOR.

Application filed June 3, 1921.

My invention relates to insulators and particularly to insulators of the link type.

One object of my invention is to provide an insulator of the above indicated character, that shall have portions so shaped to conform to the flow lines of the electrostatic field thereof andsurfaecs so disposed at right angles to the flow lines of said field as to improve the operating characteristics thereof.

A second object of my .invention is to provide a link-type insulator of refractory material that shall comprise walls and other portions of such relation and uniform thickness as to avoid the defects sometimes caused in unequal masses of refractory material during the firing thereof.

A further object of -my invention is to provide an insulator of the link type that shall comprise a substantially spherical main central body portion from which a single integral petticoat, extending in one general direction therefrom, may have an outer surface approaching a portion of the sphere in substantially tangential relation thereto.

In Patent No. 1,129,520, granted to the Vestinghouse Electric and Manufacturing Company, February 28, 1915, upon an application filed by K. C. Randall, S. WV. Farnsworth and C. LeG. Fortescue, is set forth the principle that an insulating body having its surfaces conforming to the flow lines of the electrostatic field surrounding it provides substantially the same insulating value as air.

This patent also shows an insulator having an equipotential surface or, in other words, a surface that is, at every point, sub

- stantially at right angles to the flow lines of said field.

In Patent No. 1,374,998, granted to the lVestinghouse Electric and Manufacturing Company, April 19, 1921, upon an application filed by C. LeGr. Fortescue and G. I. Gilchrest, the features of field-conforming or fiow-line surfaces and equipotential surfaces are shown and described in connection with an insulator of the pin type. To the best of my knowledge, these features have never been embodied in an insulator of the link type.

In the process of firing a porcelain insulator, adjacent masses of porcelain of different volumes sometimes cause fissures and weak portions, at the positions of joinder Serial No. 474,728.

between them, by reason of unequal expan sion. These fissures or weak portions are frequently hidden in the body of the insu lator and certain of them, while initially of insuflicient magnitude to cause failure under electrical and mechanical tests, develop under different temperature conditions, while in service, to cause failure.

A refractory insulator of the link type, by reason of its peculiar shape, is particularly subject to the defects caused by run even masses and such an insulator, which avoids these defects and, at the same time, embodies equipotential and flow-line surfaces, presents a different problem than an insulator of the pin or other types.

In practicing my invention, I provide a refractory insulator of the link type in which a petticoat portion of substantially paraboloid bowl shape is, by reason of its form and dimensions, disposed substantially everywhere on its surface at right angles to the flow lines of its electrostatic field. A substantially spherical body portion, integral with the pctticoat portion, is of such uniform mass relation to the petticoat as to avoid the above mentioned defects and is, also, shaped to have portions conforming to the How lines of the electrostatic field.

Figure 1 of the accompanying drawing, is a side view, partially in elevation and partially in section, of a pair of insulator units embodying my invention, and

Fig. 2 is a sectional view of one of the units of Fig. 1 taken at right angles thereto.

An insulator, of the link-type embodying my invention, comprises, in general, a 1

rality of preferably refractory or porcelain units 1 constituting the alternate links in a flexible series, similar to an ordinary metal. chain, in which the other links are metal connecting devices 2. The latter, constituting no part of my present invention, will not be described in detail but they comprise preferably cylindrical rods or wires 3 bent to U-shape and connected, at their free ends, to suitable members 4.

The electrostatic field surrounding a linktype insulator has been found by test to be substantially as shown by dotted lines in connection with the upper unit of Fig. 1. This test consists in cutting an opening conforming to the central-planecontour of the insulator in a piece of cardboard or other member and placing the cardboard or other member in the central plane of the insulator with the insulator and the cz'wdboard in a horizontal plane. When mica (lake particles are placed on the cardboard, and the metal terminal or connecting members are sub mitted to a relatively great difference of potential, the mica li lies arrange themselves in accordace with the flow lines of the elecic field similarly to the arrangement e P he 1. to i v r held.

o the links of an ordinar I nsulated from each other, each provided with a cenof substantially semispherieal e fl to the inner surfaces of the bowl or p coat.

The bottom closed end of the bowl or pettieoat, also being semi-spherical in outer contour, taken with the semi-spherical portion 7 a single mass, form a main cen' tral mass or body portion of uniform substantially spherical form. The remainder of the petticoat extends in one general direcspherical mass and'has he metal members 3 may y ts 5 T tion from the central its outer surface neferably approaching the central mass along lines that are substantially tune-e thereto.

The above-described construction prevents the concentration of electrostatic stresses and the consequent flash-over at voltages below that of the full ability of the insulator to withstand, as set forth in the above mentioned patents. Further, the pet-ticoats 5, being constructed of uniform thickness throughout and the main body portion being of symmetrical form, the likelihood of (lefects, caused during the tiring operation by uneven mass is materially reduced.

The portion 7 is symmetrically flared at its intersect-ion with the petticoat to better distribute mechanical stresses between it and the bowl but is, over the major port-ion of its surface, shaped to conform totheelectrostatic flow lines, as indicated by the surfaces 8. A spaee9, between the portion 7 and the inner bottom surface of the bowl, constitutes an opening; for the reception of the lower metal member 3 and the opening 10 through the portion 7, which is provided for the reception of the upper metal member 2, is centrally disposed in the portion 7 to render the walls of the latter uniformaml of such mass or thickness with respect to the bowl as to prevent the formation of fissures during the tiring operation.

an insulator constructed in accordance with my invention is not only formed to proit is the combination of these two features and the individual adyantages of each which render the insulator more durable and effective.

lVhile l have shown and described a particular form of my invention, changes may be effected therein, without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. An insulator comprising an insulating member having; a portion of substantially paraboloid shape, the inner and outer surfaces of which are spaced substantially the same distance throughout, entirely within the parabolid contour, and a substantially spherical body portion having a central opening and walls of uniform thickness.

2. A link insulator comprising a central substantially spherical body portion and a single etticoat portion inte ceptina ,the same and extendinginone gene al direction therefrom, the walls of said portions being; of substantially uniform thickness throughout, except at positions adjacent :to intercepting surfaces thereof.

In testimony wherof, I have hereunto subscribed my name this 9th day of May, 1921. 

